Whey to go! Could the cheese byproduct heat our homes and fuel our cars?

Name: Whey.

Age: As old as milk.

Appearance: Translucent, yellow-tinged.

What is it? Whey is what remains after you’ve made cheese: the milk curdles, the curds are strained and the whey is left over.

Yeah, but what’s in it? About 75% to 93% of it is water. The rest is lactose, protein and fat. Salty whey, produced when cheese curds are salted early in the process, also contains a lot of salt – as much as 10%.

What is it used for? Whey can be used to produce more cheese and cheese-style foods – ricotta, manouri and the caramel-like Norwegian spread brunost are made from whey – and the protein can be extracted for nutritional supplements. But salty whey is generally considered a waste product.

How much waste are we talking about? Britain produces 95,000 tonnes of salty whey annually and disposing of it presents an environmental challenge, in part because it’s so salty.

Surely technology can meet the challenge. Can’t we put the whey on a rocket and crash it on to the moon? We may not have to. Researchers at Heriot-Watt University in Edinburgh, working with the space tech company Take Root Bio, have devised a method for turning salty whey into fuel.

Actual fuel? Yes – it could heat homes or power your car.

Will my exhaust smell like cheese? No word on that yet.

How do they do it? The sugars in the whey are subjected to a “bio-based” process.

What a weird idea. Not, however, a new one. In 2021, the then Prince Charles burnished his green credentials by running his Aston Martin on bioethanol made from whey and surplus wine.

Surplus wine? That sounds like a royal family problem. Bioethanol has fallen out of favour as a green fuel since. The salty whey research is about adding value to byproducts that “still contain valuable components but can be challenging to manage”, according to Heriot-Watt’s Dr Jane White.

So is whey the cheap petrol of tomorrow? Whey is pretty expensive. High demand for protein supplements – largely driven by their recommendation to patients on weight-loss drugs – has pushed up the price of whey-protein concentrate. Some suppliers have already sold out for the rest of the year.

Wine surpluses, whey shortages – what crazy times we live in. I’ll admit it, I did not see any of this coming.

Do say: “To transform whey – something regarded as waste – into something of value can provide real benefit to cheese manufacturers and the environment.”

Don’t say: “Drive caerphilly, your majesty.”